These normals! They have always confused me.

If I scale a normal (say 100 times larger)
are the normal patterns still the same depth
relative to their size on the surface?

It seems to me that it depends on the pattern
used and I find that confusing.

OK I have a sphere with a bozo normal.
Now I scale the sphere 100 times larger
BEFORE the normal is added and I also scale
the camera and light_source 100 times larger.
To make the normal look the same way as before
I scale it 100 times larger, but I also have
to multiply the pattern depth by 100 (bozo 1
becomes bozo 100). Now the normal looks the
same as before.

So if you scale a normal X times larger you
also have to multiply the depth of the pattern
with X.

That is true for some patterns but for others
it isn't.

Now, I have a sphere with bumps pattern.
I scale the sphere 100 times larger (before the
normal is added) and I also scale the normal
100 times larger. Now I thought I'd also have to
multiply the pattern depth with 100 but I don't!

I only have to do that with the patterns which
were not original meant to be used in normals.
Am I right here?

OK but here's something that REALLY confuses me:

I have a sphere with a normal with one of these
patterns that were not original meant to be used
in normals.
Now the sphere doesn't fit in my scene. It is 100
times too big. So I want to scale down the whole
sphere with normal and everything.
I do so and suddenly the normal pattern is 100
times deeper! So deep that the before light shaded
areas is now totally black spots.

Is that a bug?
How can I scale up or down an object without
ruining the normals?

I don't want a man in my scene who are 100 times
too big!
But I also don't want a regular man who have folds
in his clothes so deep that half of his white shirt
are shaded totally black and with skin that makes
you think he has some kind of disease!

Thank you for your help and enlightenment!

Greetings,

Rune S. Johansen

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"Rune S. Johansen" wrote:

> These normals! They have always confused me.

> It seems to me that it depends on the pattern
> used and I find that confusing.

Obj { size <scale 1> normal { key_word <scale 2>} <scale 3>} 

	scale 1 affects only the size of the object. Scale 2 only the
normal. Scale 3 both. 

	I think I said that right. 

> I don't want a man in my scene who are 100 times
> too big!

> Thank you for your help and enlightenment!

	Sounds like all you have done is lost track of your {}. ctrl-[
(match bracket or parenthesis or brace, whatever it is on your
version) is a very powerful tool and one that has saved the
sanity of many a programmer.

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Matt Giwer discloses:
>
> Sounds like all you have done is lost track of your {}. ctrl-[
> (match bracket or parenthesis or brace, whatever it is on your
> version) is a very powerful tool and one that has saved the
> sanity of many a programmer.

    I am consistently amazed at the things I don't know....

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Bill DeWitt wrote:

> Matt Giwer discloses:

> > Sounds like all you have done is lost track of your {}. ctrl-[
> > (match bracket or parenthesis or brace, whatever it is on your
> > version) is a very powerful tool and one that has saved the
> > sanity of many a programmer.

>     I am consistently amazed at the things I don't know....

	Oops, ctrl+] not [ 

	Its in the search menu. Put the cursor on the opening [{( and it
finds the closing one. 

-- 
<blink>-------please--don't-----------------</blink>

http://www.giwersworld.org/artii/
http://www.giwersworld.org/artiii/

Finally up on 99/06/22 updated 07/13

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After messing around with my computer's clock Outlook
Express won't show all messages so I can't see all replies
to my first message.
Anyway I saw Matt Giwer saying something like:

>Sounds like all you have done is lost track of your {}.

To show that that's not the problem I have made an example.
Change the value "Scale" to high and low values like 100
and 0.01 and you will see that the normal changes.

// Start of example

#declare Scale = 1;

camera {
   location -3*z
   look_at 0
   scale Scale
}

light_source {<10,20,-30>*Scale, color 1}

#declare Sphere =
sphere {
   0, 1
   pigment {color rgb 1}
   normal {bozo 1 scale 0.2}
}

object {Sphere scale Scale}

// End of example

I also have this scene with BlobMan scaled 40 times down.
His skin looks VERY nubbly (if that is the correct word).
Also when he is scaled very large his skin looks way too smooth.

I don't know if that normal behavior is a bug or not.
If it isn't how can I get around it?

Thanks!

Rune S. Johansen

---
Visit The RSJ Website at http://welcome.to/rsj
for 3D images including still lives, dragons,
mathematical shapes, and more. Stereograms,
tutorials, The POV Desktop Theme, hundreds of
raytracing jokes, miscellaneous other things,
and a lot of fun!

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"Rune S. Johansen" wrote:

> I don't know if that normal behavior is a bug or not.
> If it isn't how can I get around it?
> 
> Thanks!
> 
> Rune S. Johansen

If it doesn't work through several scaling operations then simply apply the
normal to the object at it's final scale and adjust the normal to appear
how you wish it to look.

Say for example you have a blob man that is 10 pov units tall but you
want it 1 unit tall. Scale it by 0.1 then apply the normal to it after
the scale statement. It may not be as predictable as you prefer but you
should still be able to get the normal pattern to appear as you wish
it to.

-- 
Ken Tyler

See my 700+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

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Ken wrote:
>"Rune S. Johansen" wrote:
>
>> I don't know if that normal behavior is a bug or not.
>> If it isn't how can I get around it?
>>
>> Thanks!
>>
>> Rune S. Johansen
>
>If it doesn't work through several scaling operations then simply apply the
>normal to the object at it's final scale and adjust the normal to appear
>how you wish it to look.
>
>Say for example you have a blob man that is 10 pov units tall but you
>want it 1 unit tall. Scale it by 0.1 then apply the normal to it after
>the scale statement. It may not be as predictable as you prefer but you
>should still be able to get the normal pattern to appear as you wish
>it to.

Unfortunately that isn't always enough. :-(

My BlobMan has clothes. That means he is made up of multiple objects each
with separate textures.
When it is an object that has already been #declared you can only add one
texture to the whole object afterwards and that isn't enough if you need an
object with different textures on the different parts.
Besides, if textures have already been added to the object you can't
overwrite them.

Greetings,

Rune S. Johansen

---
Visit The RSJ Website at http://welcome.to/rsj
for 3D images including still lives, dragons,
mathematical shapes, and more. Stereograms,
tutorials, The POV Desktop Theme, hundreds of
raytracing jokes, miscellaneous other things,
and a lot of fun!

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